Difference Between valence bond theory (VBT) and Molecular orbital theory (MOT)

Difference Between VBT and MOT

VBT and MOT describe two dissimilar kinds of bondings. The valence bond theory (VBT) explains bonding behavior in metals. The molecular orbital theory (MOT) describes bonding behavior in molecules.

VBT

• • Atomic orbitals are mono-centric.
  • Atoms, which are involved in the bond formation, maintain their individual nature.
  • VBT has simplicity and convenience.
  • Resulting Molecular Orbital is obtained by the combination of the two wave functions of two unpaired electrons.
  • In VBT, some of the valence electrons are indicated as unshared and uninvolved in the formation of the molecule.
  • VBT failed to explain the paramagnetic behavior of oxygen.

MOT

• • Molecular orbitals are poly-centric.
  • Atomic orbitals, which form molecular orbitals, do not retain their individual nature.
  • MOT is somewhat complex, especially molecules contain more than two atoms.
  • The formation of the Molecular Orbitals is based on the LCAO approximation method. Atomic Orbitals corresponding of the Valency Shell of two only takes part in the formation of Molecular Orbitals.
  • MOT method shows that all the electrons of the valence shells of the atoms of a molecule take part in the bonding.
  • MOT successfully explains the paramagnetic behavior of oxygen.